The unidentified boaters, ages 53, 40 and 16, were spotted clutching to the hull of the 16-foot fiberglass vessel at 4:30 a.m. about 2 miles southeast of Atsena Otie Key, according to the Coast Guard. The boat is believed to have capsized about 5 p.m.

The Coast Guard in St. Petersburg received a 911 call at 7 p.m. Sunday from a concerned family member after the boaters failed to come home as scheduled.

They men left from Cedar Key and planned to sail around Atsena Otie Key, about a mile off shore.

It was unclear when the boat capsized.

There was a small-craft advisory throughout the day Sunday, with winds of about 20 knots and gusts of up to 30 knots. Seas were 2 to 3 feet.

The boat had no motor, lights, electronics or emergency equipment.

A Coast Guard rescue helicopter, rescuers from Levy County and the Florida Fish and Wildlife Conservation Commission searched for seven hours before the boaters were found.

They were spotted from the Coast Guard's HH-60 Jayhawk helicopter, clutching to the capsized hull, after seven hours of searching. A rescue swimmer was lowered, and the boaters were plucked from the vessel.

"This case could have turned out differently," said Coast Guard search and rescue coordinator Richard Hutchinson in a statement. "These mariners are lucky to be alive."